Radiation sensing thermoplastic composite panels

ABSTRACT

A storage phosphor panel can include an extruded inorganic storage phosphor layer including a thermoplastic polymer and an inorganic storage phosphor material, where the extruded inorganic storage phosphor panel has an image quality comparable to that of a traditional solvent coated inorganic storage phosphor screen. Further disclosed are certain exemplary method and/or apparatus embodiments that can provide inorganic storage phosphor panels including reduced noise. Further disclosed are certain exemplary method and/or apparatus embodiments that can include inorganic storage phosphor layer including at least one polymer, an inorganic storage phosphor material, and a copper phthalocyanine based blue dye.

FIELD OF THE INVENTION

The invention relates generally to the field of inorganic storagephosphor materials. More specifically, the invention relates to meltextrudable and/or injection moldable and/or hot-melt pressablecomposites of inorganic storage phosphor materials and thermoplasticand/or thermoset polymers and methods for making and/or using the same.

BACKGROUND OF THE INVENTION

Near the beginning of the 20^(th) century, it was recognized that amedically useful anatomical image could be obtained when a filmcontaining a radiation-sensitive silver halide emulsion is exposed toX-radiation (X-rays) passing through the patient. Subsequently, it wasrecognized that X-ray exposure could be decreased considerably byplacing a radiographic phosphor panel adjacent to the film.

A radiographic phosphor panel typically contains a layer of an inorganicphosphor that can absorb X-rays and emit light to expose the film. Theinorganic phosphor layer is generally a crystalline material thatresponds to X-rays in an image-wise fashion. Radiographic phosphorpanels can be classified, based on the type of phosphors used, as promptemission panels and image storage panels.

Image storage panels (also commonly referred to as “storage phosphorpanels”) typically contain a storage (“stimulable”) phosphor capable ofabsorbing X-rays and storing its energy until subsequently stimulated toemit light in an image-wise fashion as a function of the stored X-raypattern. A well-known use for storage phosphor panels is in computed ordigital radiography. In these applications, the panel is firstimage-wise exposed to X-rays, which are absorbed by the inorganicphosphor particles, to create a latent image. While the phosphorparticles may fluoresce to some degree, most of the absorbed X-rays arestored therein. At some interval after initial X-ray exposure, thestorage phosphor panel is subjected to longer wave length radiation,such as visible or infrared light (e.g., stimulating light), resultingin the emission of the energy stored in the phosphor particles asstimulated luminescence (e.g., stimulated light) that is detected andconverted into sequential electrical signals which are processed inorder to render a visible image on recording materials, such aslight-sensitive films or digital display devices (e.g., television orcomputer monitors). For example, a storage phosphor panel can beimage-wise exposed to X-rays and subsequently stimulated by a laserhaving a red light or infrared beam, resulting in green or blue lightemission that is detected and converted to electrical signals which areprocessed to render a visible image on a computer monitor. Thestimulating light may also be other sources other than a laser (such asLED lamps), that would permit stimulation of a larger area of thestorage phosphor, and the detection may be done using a two dimensionaldetector, such as a CCD or a CMOS device. Thereafter, images fromstorage phosphor panels can be “erased” by exposure to UV radiation,such as from fluorescent lamps.

Thus, storage phosphor panels are typically expected to store as muchincident X-rays as possible while emitting stored energy in a negligibleamount until after subsequent stimulation; only after being subjected tostimulating light should the stored energy be released. In this way,storage phosphor panels can be repeatedly used to store and transmitradiation images.

However, there exists a need for improved storage phosphor panels. Morespecifically, there exists a need for melt extruded or injection moldedor hot pressed inorganic storage phosphor panel has an image qualitythat is comparable to the image quality of the traditional solventcoated screen of equivalent x-ray absorbance.

SUMMARY OF THE INVENTION

An aspect of this application is to advance the art of medical, dentaland non-destructive imaging systems.

Another aspect of this application is to address in whole or in part, atleast the foregoing and other deficiencies in the related art.

It is another aspect of this application to provide in whole or in part,at least the advantages described herein.

In an aspect, there are provided exemplary melt extruded or injectionmolded or hot pressed inorganic storage phosphor panel embodimentsincluding a melt extruded or injection molded or hot pressed inorganicstorage phosphor layer comprising a thermoplastic polymer and aninorganic storage phosphor material, wherein the melt extruded orinjection molded or hot pressed inorganic storage phosphor panel has animage quality that is comparable to or better than the image quality ofthe traditional solvent coated screen of equivalent x-ray absorbance.

In another aspect, there are also disclosed exemplary inorganic storagephosphor detection system embodiments including a melt extruded orinjection molded or hot pressed inorganic storage phosphor panelcomprising a melt extruded or injection molded or hot pressed inorganicstorage phosphor layer comprising a thermoplastic olefin and aninorganic storage phosphor material;

In a further aspect, there are disclosed exemplary method embodiments ofmaking a melt extruded or injection molded or hot pressed inorganicstorage phosphor panel including providing thermoplastic polymercomprising at least one thermoplastic polymer and an inorganic storagephosphor material; and melt extruding or injection molding or hotpressing the thermoplastic polymer and the inorganic storage phosphormaterial to form a melt extruded or injection molded or hot pressedinorganic storage phosphor layer.

In a further aspect, there is disclosed an exemplary inorganic storagephosphor panel that can include an inorganic storage phosphor layerincluding at least one polymer, an inorganic storage phosphor material,and a copper phthalocyanine based blue dye, and the inorganic storagephosphor layer has a coefficient of variation in the linearized pixelvalue that is less than or equal to 0.4.

In a further aspect, there is disclosed an exemplary method that caninclude melt extruding, injection molding or hot pressing materialsincluding at least one thermoplastic polyolefin, an inorganic storagephosphor material and a copper phthalocyanine blue dye to form amanufactured inorganic storage phosphor layer, the manufacturedinorganic storage phosphor layer has a coefficient of variation in thelinearized pixel value that is less than or equal to 0.4; exposing themanufactured inorganic storage phosphor layer to x-rays to form a latentimage; and exposing the latent image in the manufactured inorganicstorage phosphor layer to excitation light to generate a digital imageof the latent image.

These objects are given only by way of illustrative example, and suchobjects may be exemplary of one or more embodiments of the invention.Other desirable objectives and advantages inherently achieved by thedisclosed invention may occur or become apparent to those skilled in theart. The invention is defined by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of theinvention will be apparent from the following more particulardescription of the embodiments of the invention, as illustrated in theaccompanying drawings. The elements of the drawings are not necessarilyto scale relative to each other.

FIGS. 1A-1C depicts exemplary portions of scintillator panels inaccordance with various embodiments of the present disclosure.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following is a description of exemplary embodiments, reference beingmade to the drawings in which the same reference numerals identify thesame elements of structure in each of the several FIGURES.

Exemplary embodiments herein provide storage phosphor panels includingan extruded storage phosphor layer with a thermoplastic polymer and astorage phosphor material, and methods of preparing thereof. It shouldbe noted that while the present description and examples are primarilydirected to radiographic medical imaging of a human or other subject,embodiments of apparatus and methods of the present application can alsobe applied to other radiographic imaging applications. This includesapplications such as non-destructive testing (NDT), for whichradiographic images may be obtained and provided with differentprocessing treatments in order to accentuate different features of theimaged subject.

An important property of the screen is its x-ray absorbance. Dependingon the specific application (orthopedic or mammography or intra-oraldental or extra oral dental or non-destructive testing of metals or . .. ), the energy and the intensity of the radiation that is incident onthe storage phosphor screen will be different. However, in order to bevalue as an x-ray imaging tool, the storage phosphor screen has to havesufficient x-ray absorbance, so as to produce a useful image. Inpractical terms, this requires that ˜40-60% of the extruded storagephosphor screen (by volume) be the storage phosphor material (bariumfluorobromoiodide or cesium bromide).

Another requirement for the storage phosphor screen is that it bereadable from either side of the screen, and in the transmission or thereflection mode, with respect to the direction of incidence of thestimulation radiation used for reading the information in the screen.And it would desirable that the screen can be handled under ambientlighting conditions or room light.

Depending on the specific imaging application (medical radiography ordental radiography or non-destructive testing), the physicalcharacteristics required of the storage phosphor panel can be widelydifferent. However, the divergent physical properties may be defined bya few key properties of the storage phosphor screen, such as its bendingresistance (http://www.taberindustries.com/stiffness-tester), tearresistance(http://jlwinstruments.com/index.php/products/test-solutions/tear-resistance-testing/)or folding resistance(https://www.testingmachines.com/product/31-23-mit-folding-endurance-tester).A summary of various methods to measure these properties is outlined in(http://ipst.gatech.edu/facultv/popil_roman/pdf_presentations/Prediction%20of%20Fold%20Cracking%20Propensity%20through%20Physical%20Testing.pdf). Allthis may be achieved using a single layer or a multi layeredarchitecture, that would include additional, coextruded layers on thescreen, that may contain particulates and/or chemistry to achieve therequired physical properties needed to accommodate the mechanics of thescanner and/or handling by the end user. Further, it is important thatthe extruded storage phosphor screen be recyclable; i.e., it isnecessary that the composition of the screen is such that they canre-used to make the storage phosphor screen, and/or the storage phosphorpart of the screen can be reused to manufacture a new screen.

The stimulation wavelength and the emission wavelength of the storagephosphor panel are generally determined by the specific storagephosphor. The peak stimulation wavelength for the commonly used storagephosphors, the stimulation wavelength is fairly broad, and is in theregion of 550-700 nm. However, the stimulated emission for the europiumdoped barium fluorobromoiodide storage phosphor has peak around 390 nm.

FIG. 1 depicts a portion of an exemplary storage phosphor panel 100 inaccordance with various embodiments of the present disclosure. As usedherein, “storage phosphor panel” is understood to have its ordinarymeaning in the art unless otherwise specified, and refers to panels orscreens that store the image upon exposure to X-radiation and emit lightwhen stimulated by another (generally visible) radiation. As such,“panels” and “screens” are used interchangeably herein. It should bereadily apparent to one of ordinary skill in the art that the storagephosphor panel 100 depicted in FIGS. 1A-1C represents a generalizedschematic illustration and that other components can be added orexisting components can be removed or modified.

Storage phosphor panels disclosed herein can take any convenient formprovided they meet all of the usual requirements for use in computedradiography. As shown in FIG. 1A, the storage phosphor panel 100 mayinclude a support 110 and a melt extruded or injection molded or hotpressed storage phosphor layer 120 disposed over the support 110. Anyflexible or rigid material suitable for use in storage phosphor panelsand does not interfere with the recyclability of storage phosphor screencan be used as the support 110, such as glass, plastic films, ceramics,polymeric materials, carbon substrates, and the like. In certainembodiments, the support 110 can be made of ceramic, (e.g., Al₂O₃) ormetallic (e.g., Al) or polymeric (e.g., polypropylene) materials. Alsoas shown in FIG. 1A, in an aspect, the support 110 can be coextrudedwith the storage phosphor layer 120. The support may be transparent,translucent, opaque, or colored (e.g., containing a blue or a blackdye). Alternatively, if desired, a support can be omitted in the storagephosphor panel.

In another aspect, an anticurl layer may be coextruded on either side ofthe support, if a support is used, or on side of the storage phosphorscreen, to manage the dimensional stability of the storage phosphorscreen.

The thickness of the support 110 can vary depending on the materialsused so long as it is capable of supporting itself and layers disposedthereupon. Generally, the support can have a thickness ranging fromabout 50 μm to about 1,000 μm, for example from about 80 μm to about1000 μm, such as from about 80 μm to about 500 μm. The support 110 canhave a smooth or rough surface, depending on the desired application. Inan embodiment, the storage phosphor panel does not comprise a support.

The storage phosphor layer 120 can be disposed over the support 110, ifa support is included. Alternatively, the storage phosphor layer 120 canbe melt extruded or injection molded or hot pressed independently asshown in FIG. 1B, or melt extruded or injection molded or hot pressedtogether with an opaque layer, and anticurl layer, and combinationsthereof, e.g., shown as layer 150, in FIG. 1A and FIG. 1C.

The storage phosphor layer 120 can include a thermoplastic polymer 130and a storage phosphor material 140. The thermoplastic polymer 130 maybe a polyolefin, such as polyethylene, a polypropylene, and combinationsthereof, or a polyurethane, a polyester, a polycarbonate, a silicone, asiloxane, a polyvinyl chloride (PVC), a polyvinylidine chloride (PVdC).In an aspect, the polyethylene can be high density poly low densitypolyethylene (LDPE), medium density polyethylene (MDPE), linear lowdensity polyethylene (LLDPE), very low density polyethylene (VLDPE), andthe like. In a preferred embodiment, the thermoplastic polymer 130 islow density polyethylene (LDPE). The thermoplastic polymer 130 can bepresent in the storage phosphor layer 120 in an amount ranging fromabout 1% to about 50% by volume, for example from about 10% to about 30%by volume, relative to the total volume of the storage phosphor layer120.

As used herein, “storage phosphor particles” and “stimulable phosphorparticles” are used interchangeably and are understood to have theordinary meaning as understood by those skilled in the art unlessotherwise specified. “Storage phosphor particles” or “stimulablephosphor particles” refer to phosphor crystals capable of absorbing andstoring X-rays and emitting electromagnetic radiation (e.g., light) of asecond wavelength when exposed to or stimulated by radiation of stillanother wavelength. Generally, stimulable phosphor particles are turbidpolycrystals having particle diameters of several micrometers to severalhundreds of micrometers; however, fine phosphor particles of submicronto nano sizes have also been synthesized and can be useful. Thus, theoptimum mean particle size for a given application is a reflection ofthe balance between imaging speed and desired image sharpness.

Stimulable phosphor particles can be obtained by doping, for example,rare earth ions as an activator into a parent material such as oxides,nitrides, oxynitrides, sulfides, oxysulfides, silicates, halides, andthe like, and combinations thereof. As used herein, “rare earth” refersto chemical elements having an atomic number of 39 or 57 through 71(also known as “lanthanoids”). Stimulable phosphor particles are capableof absorbing a wide range of electromagnetic radiation. In exemplarypreferred embodiments, stimulable phosphor particles can absorbradiation having a wavelength of from about 0.01 to about 10 nm (e.g.,X-rays) and from about 300 nm to about 1400 nm (e.g., UV, visible, andinfrared light). When stimulated with stimulating light having awavelength in the range of visible and infrared light, stimulablephosphor particles can emit stimulated light at a wavelength of fromabout 300 nm to about 650 nm.

Suitable exemplary stimulable phosphor particles for use herein include,but are not limited to, compounds having Formula (I):MFX_(1-z)I_(z) uM^(a)X^(a) :yA:eQ:tD  (I)wherein M is selected from the group consisting of Mg, Ca, Sr, Ba, andcombinations thereof;

X is selected from the group consisting Cl, Br, and combinationsthereof;

M^(a) is selected from the group consisting of Na, K, Rb, Cs, andcombinations thereof;

X^(a) is selected from the group consisting of F, Cl, Br, I, andcombinations thereof;

A is selected from the group consisting of Eu, Ce, Sm, Th, Bi, andcombinations thereof;

Q is selected from the group consisting of BeO, MgO, CaO, SrO, BaO, ZnO,Al₂O₃, La₂O₃, In₂O₃, SiO₂, TiO₂, ZrO₂, GeO₂, Nb₂O₅, Ta₂O₅, ThO₂, andcombinations thereof;

D is selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, andcombinations thereof;

z is from about 0.0001 to about 1;

u is from about 0 to about 1;

y is from about 0.0001 to about 0.1;

e is from 0 to about 1; and

t is from 0 to about 0.01.

The amounts represented by “z”, “u”, “y”, “e”, and “t” are molaramounts. The same designations appearing elsewhere in this disclosurehave the same meanings unless otherwise specified. In Formula (I),preferably, M is Ba; X is Br; M^(a) is selected from the groupconsisting of Na, K, and combinations thereof; X^(a) is selected fromthe group consisting of F, Br, and combinations thereof; A is Eu; Q isselected from the group consisting of SiO₂, Al₂O₃, and combinationsthereof; and t is 0.

Other exemplary stimulable phosphor particles for use herein include,but are not limited to, compounds having Formula (II):(Ba_(1-a-b-c)Mg_(a)Ca_(b)Sr_(c))FX_(1-z)I_(z)rM^(a)X^(a) :yA:eQ:tD  (II)wherein X, M^(a), X^(a), A, Q, D e, t, z, and y are as defined above forFormula (I); the sum of a, b, and c, is from 0 to about 0.4; and r isfrom about 10⁻⁶ to about 0.1.

In Formula (II), preferably X is Br; M^(a) is selected from the groupconsisting of Na, K, and combinations thereof; X^(a) is selected fromthe group consisting of F, Br, and combinations thereof; A is selectedfrom the group consisting of Eu, Ce, Bi, and combinations thereof; Q isselected from the group consisting of SiO₂, Al₂O₃, and combinationsthereof; and t is 0.

Further exemplary stimulable phosphor particles for use herein include,but are not limited to, compounds having Formula (III):M¹⁺X_(a)M²⁺X′₂ bM³⁺X″3:cZ  (III)wherein M is selected from the group consisting of Li, na, K, Cs, Rb,and combinations thereof;

M²⁺ is selected from the group consisting of Be, Mg, Ca, Sr, Ba, Zn, Cd,Cu, Pb, Ni, and combinations thereof;

M³⁺ is selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Pm,Sm, Eu, Gd, Tb, Dy Ho, Er, Tm Yb, Lum Al, Bi, In, Ga, and combinationsthereof;

Z is selected from the group consisting of Ga⁺, Ge²⁺, Sn²⁺, Sb³⁺, As³⁺,and combinations thereof;

X, X′ and X″ can be the same or different and each individuallyrepresents a halogen atom selected from the group consisting of F, Br,Cl, I; and

0≤a≤1; 0≤b≤1; 0≤c≤0.2.

Preferred stimulable phosphor particles represented by Formulas (I),(II), or (III) include europium activated barium fluorobromides (e.g.,BaFBr:Eu and BaFBrI:Eu), cerium activated alkaline earth metal halides,cerium activated oxyhalides, divalent europium activated alkaline earthmetal fluorohalides, (e.g., Ba(Sr)FBr:Eu²⁺) divalent europium activatedalkaline earth metal halides, rare earth element activated rare earthoxyhalides, bismuth activated alkaline metal halide phosphors, andcombinations thereof.

An alternative to the Eu doped BaFBrI type storage phosphor is, Eu dopedCsBr storage phosphor. This is generally used in the form a binderlessstorage phosphor screen, where the needle shaped Eu doped CsBr particlesare generated by vapor deposition of the material on a substrate, whichis then sealed water impermeable material. Such needle shaped europiumdoped cesium bromide storage phosphor screen has an emission peak around450 nm.

The thermoplastic polymer and the inorganic storage phosphor materialare melt compounded to form composite thermoplastic particles which arethen melt extruded or injection molded or hot pressed to form theinorganic storage phosphor layer. For example, the compositethermoplastic particles can be prepared by melt compounding thethermoplastic polymer with the inorganic storage phosphor material usinga twin screw compounder. The ratio of thermoplastic polymer to inorganicstorage phosphor material (polymer:inorganic storage phosphor) can rangefrom about 1:100 to about 1:0.01, by weight or volume, preferably fromabout 1:1 to about 1:0.1, by weight or volume. The composition mayinclude inorganic, organic and/or polymeric additives to manage imagequality and/or the physical properties of the extruded storage phosphorscreen. Examples of the additives include, a blue dye (e.g., ultramarineblue, copper phthalocyanine, . . . ) for managing image quality,surfactants (e.g., sodium dodecyl sulfate) for managing the colloidalstability of the storage phosphor particles, polymers (e.g., ethylenevinylacetate) for managing the rheology of the composite. During meltcompounding, the thermoplastic polymer and the inorganic storagephosphor material can be compounded and heated through multiple heatingzones. For example, in the case of polyolefins, the temperature of theheating zones can vary from ca. 170° C.-250° C., depending on thespecific composition of the polymer/additive blends that are used, andthe period of time in each zone depends on the polymer used and thetemperature of the heating zone. Generally, the polymer can be heatedfor a time and temperature sufficient to melt the polymer andincorporate the inorganic storage phosphor material without decomposingthe polymer. The period of time in each zone can range from about 1second to about 1 minute. Upon exiting the melt compounder, thecomposite thermoplastic material can enter a water bath to cool andharden into continuous strands. The strands can be pelletized and driedat about 40° C. The screw speed and feed rates for each of thethermoplastic polymer 130 and the inorganic storage phosphor material140 can be adjusted as desired to control the amount of each in thecomposite thermoplastic material.

Alternatives to melt compounding include the creation of the compositemixture in an appropriate solvent where the polymer is dissolved ordispersed and inorganic storage phosphor particles are dispersed,followed by the evaporation of the solvent and the milling of thepolymer/inorganic storage phosphor composite mixture is pelletized usinggrinders, cryo-grinder, densifiers, agglomerators, or any other suitabledevice.

The inorganic storage phosphor/thermoplastic polymer composite materialcan be melt extruded or injection molded or hot pressed to form theinorganic storage phosphor layer in which the inorganic storage phosphormaterial is intercalated (“loaded”) within the thermoplastic polymer.For example, the inorganic storage phosphor/thermoplastic polymercomposite layer can be formed by melt extruding or injection molding orhot pressing the composite thermoplastic material. Without being limitedby theory, it is believed that forming the inorganic storagephosphor/thermoplastic composite layer by melt extrusion or injectionmolding or hot pressing increases the homogeneity of the inorganicstorage phosphor layer, and eliminates the undesirable “evaporatedspace” generated when the solvent is evaporated in the traditionalsolvent-coated panels. A melt extruded or injection molded or hotpressed inorganic storage phosphor/thermoplastic composite panelaccording to the present disclosure can have comparable image quality,as compared to the traditional solvent coated panels, along withimproved mechanical and environmental robustness.

In the case of the inorganic storage phosphor/thermoplastic polymercomposite layer being melt extruded or injection molded or hot pressedin combination with a support layer, the melt processing parameters(temperature, screw speed and pump speed in the case of melt extrusionand injection molding, and temperature and pressure in the case of hotpressing) can be adjusted to control the thickness for each of theinorganic storage phosphor/thermoplastic polymer composite layer and thesupport layer, individually.

The thickness of the inorganic storage phosphor/thermoplastic compositelayer can range from about 10 μm to about 1000 μm, preferably from about50 μm to about 750 μm, more preferably from about 100 μm to about 500μm.

Optionally, the melt extruded or injection molded or hot pressedinorganic storage phosphor panel can include a protective overcoatdisposed over the inorganic storage phosphor/thermoplastic compositelayer, which provides enhanced mechanical strength and scratch andmoisture resistance, if desired.

In an embodiment, a scintillation detection system can include thedisclosed storage phosphor panel 100 coupled, inserted or mounted to atleast one storage phosphor panel reader/scanner 160. Choice of aparticular storage phosphor reader will depend, in part, on the type ofstorage phosphor panel being fabricated and the intended use of theultimate device used with the disclosed storage phosphor panel.

Image Quality Assessment

The image quality assessments were done as described below. The extrudedplate is adhered to a black PET (Toray Lumirror X30—10 mil) supportusing an optically clear adhesive (3M 8141). The solvent coated platesalready had a PET support, and were not subjected to the adhesion of anadditional PET support. This plate is then placed in the CarestreamHealth CS2200 x-ray generator and exposed to an x-ray exposure of 70 kV,7 mA, and 0.16 sec. This exposed plate, kept in subdued ambient light,is then scanned in the Carestream Health CS7600 intra oral-dentalscanner, in the super high resolution mode. The flat field image issaved as a linearized dicom file. The average linearized pixel value andthe standard deviation is calculated using a dicom viewer, and thecoefficient of variation (COV) is calculated as the ratio of thestandard deviation to the average linearized pixel value.

The plates are all dental size 2 with an area of approximately 12.71cm².

Comparative Example 1

A CS7600 intra oral computed radiography plate SN ED005947 was used as acomparative example.

Comparative Example 2

A Durr Dental intra oral computed radiography plate CE 0124 was used asa comparative example.

Comparative Example 3

A solvent coated storage phosphor panel was prepared by mixing a BFBI:Euphosphor with a solvent package and a binder. The solvent package isprepared by mixing 78 grams of Methylene chloride, 6 grams of Methanol,and 15 grams of 1,3 Dioxolane. The binder is Permuthane (Stahl, PeabodyMass.), which is diluted to 15% in a solvent package listed above. Theother ingredients are added to the weight percentage as specified. Thefilm stabilizer (tetrabutyl ammonium thiosulfate) is a 20% solution thatis added to help prevent iodide formation in both the liquid and coatedstate. The blue dye (Ultramarine blue from Nubiola) is added at a levelequivalent to 1200 ppm based on phosphor weight.

TABLE 1 Component Percentage Permuthane Solution 4.063 Methylenechloride 27.25 Methanol 2.15 1,3 Dixolane 5.25 Dowanol PM 0.35 FilmStabilizer 0.35 UltraMarine Blue 0.073 Phosphor 60.526 Total 100.0The overcoat layer consists of a mixture of Ethyl acetate, Acetone,Methyl methacrylate polymer (Elvacite 2051), 1-Propene,1,1,2,3,3,3-hexafluoro-polymer with 1,1-difluoroethene (Superflex2500-20), N,N-Ethylenebis(stearamide) (Superslip 6350), and polymethylmethacrylate matte beads. The ratio of components for the solution islisted below:

TABLE 2 Component Percentage Ethyl Acetate 67.875 Acetone 22.625Superflex 2500-20 2.74 Elvacite 2051 6.39 SuperSlip 6350 0.183polymethyl methacrylate 0.183 matte bead Total 100.0The phosphor solution was coated onto a PET base support and dried usingheated air sections to flash off the solvents, with a resultant phosphorcoverage 41 g/ft². The overcoat solutions were coated on top of thephosphor layer and dried using heated air sections to flash off thesolvents, with resultant overcoat coverage of nominally 0.65 g/ft2.

Comparative Example 4

Composite Thermoplastic Particle Production

Inorganic storage phosphor/thermoplastic composite pellets according tothe present disclosure were prepared comprising 86% wt. bariumflurobromoiodide (BFBrI) and 14% wt low density polyethylene (LDPEEM811A, available from Westlake Longview Corp. of Houston, Tex.). Theinorganic storage phosphor particles was characterized using theMicrotrac 9200 FRA, to have 95% of the particles to be <5.97 microns and50% of the particles to be <3.51 microns in diameter.

The formulation involved blending and compounding of the EM811A polymerresin with the the BFBrI powder using a Leistritz GL-400 twin screwcompounder. The screw speed was set at 300 RPM. The die temperature wasset to 220° C. and 10 heating zones within the compounder were set tothe temperatures shown in Table 3 below:

TABLE 3 Zone 1 2 3 4 5 6 7 8 9 10 Temp 220 220 220 220 220 220 220 220220 220 (° C.)After exiting the die, the inorganic storage phosphor/thermoplasticcomposite pellets, comprising LDPE loaded with BFBrI, entered a 25° C.water bath to cool and hardened into continuous strands. The strandswere then fed into a pelletizer and dried at 40° C.Extrusion of Inorganic Storage Phosphor Layer

The pelletized composite thermoplastic materials were loaded into asingle screw Killion extruder. Within the extruder, heating zones wereset to the temperatures shown in Table 2

TABLE 4 Killion Extruder Zone Temp 1 390° F. 2 420° F. 3 430° F. 4 430°F. Gate 430° F. Die 430° F.The pelletized material (composite thermoplastic) was extruded through asingle die with the die temperature set at 430° F. form an extrudedinorganic storage phosphor panel in the thickness range of 100-200microns.

Inventive Example 1

Composite Thermoplastic Particle Production

A sample was prepared as described in comparative example 4, with thedifference that it contained ultramarine blue dye at a level of 1600 ppmwith respect to the phosphor.

Inventive Example 2

Composite Thermoplastic Particle Production

A sample was prepared as described in inventive example 1, with aprimary difference being the blue dye is copper phthalocyanine insteadof ultramarine blue, at a level of approximately 12.5 ppm with respectto the phosphor.

Inventive Example 3

Composite Thermoplastic Particle Production

A sample was prepared as described in inventive example 1, with aprimary difference being the blue dye is copper phthalocyanine insteadof ultramarine blue, at a level of approximately 50 ppm with respect tothe phosphor.

Inventive Example 4

Composite Thermoplastic Particle Production

A sample was prepared as described in inventive example 1, with aprimary difference being the blue dye is copper phthalocyanine insteadof ultramarine blue, at a level of approximately 50 ppm with respect tothe phosphor, and the use of a polymer processing additive (PSA), KynarSuperflex® 2500-20, from Arkema, at a level of 1000 ppm with respect tothe phosphor.

Analysis

TABLE 5 Relative CV Noise (with respect Average Std. (coefficient of tocomparative Sample Speed Dev. variation CV) example 1) ComparativeExample 1 53055 326 0.61% 100% Comparative Example 2 53991 274 0.51% 83% Comparative Example 3 53966 332 0.62% 100% Comparative Example 454266 336 0.62% 101% Inventive Example 1 56281 231 0.41%  67% InventiveExample 2 55918 239 0.43%  70% Inventive Example 3 58903 163 0.28%  45%Inventive Example 4 59460 121 0.20%  33%

In certain exemplary method and/or apparatus embodiments, the copperphthalocyanine blue dye is configured to reduce noise effects.

Exemplary method and/or apparatus embodiments can provide free standinginorganic storage phosphor panels that can include an inorganic storagephosphor layer including at least one polymer, an inorganic storagephosphor material that has 95% of the particles to be ≤6.8 microns indiameter, and a blue dye, and the inorganic storage phosphor layer has acoefficient of variation in the linearized pixel value that is less thanor equal to 0.40.

Exemplary method and/or apparatus embodiments can provide free standinginorganic storage phosphor panels that can include an inorganic storagephosphor layer including at least one polymer or thermoplasticpolyolefin, an inorganic storage phosphor material that has 95% of theparticles to be ≤6.8 microns in diameter, and 50% of the particles to be≤3.8 microns in diameter and a blue dye, and has a coefficient ofvariation in the linearized pixel value that is less than or equal to0.40.

Exemplary method and/or apparatus embodiments can provide free standinginorganic storage phosphor panels that can include an inorganic storagephosphor layer including at least one polymer, an inorganic storagephosphor material, and a blue dye, where the storage phosphor layer hasa coefficient of variation in the linearized pixel value that is lessthan or equal to 0.40. Certain exemplary method embodiments can providemethods including combining materials including at least one polymer, aninorganic storage phosphor material and a blue dye to form amanufactured inorganic storage phosphor layer, which has a coefficientof variation in the linearized pixel value that is less than or equal to0.40; exposing the manufactured inorganic storage phosphor layer tox-rays to form a latent image; and exposing the latent image in themanufactured inorganic storage phosphor layer to excitation light togenerate a digital image of the latent image. Certain exemplary methodembodiments can provide methods including melt extruding, injectionmolding or hot pressing materials comprising at least one thermoplasticpolyolefin, an inorganic storage phosphor material that has 95% of itsparticles to be ≤6.8 microns in diameter, and 50% of the particles to be≤3.8 microns in diameter and a blue dye to form a manufactured inorganicstorage phosphor layer, which has a coefficient of variation in thelinearized pixel value that is less than or equal to 0.40; exposing themanufactured inorganic storage phosphor layer to x-rays to form a latentimage; and exposing the latent image in the manufactured inorganicstorage phosphor layer to excitation light to generate a digital imageof the latent image. In one embodiment, the combining is by meltextruding, injection molding or hot pressing. In one embodiment, alatent image in the storage phosphor screen is read using reflectancescanning in a reflectance mode or transmissive scanning in atransmissive mode. In some embodiments, the polymer is a thermoplasticpolyolefin. In some embodiments, the blue dye is a copper phthalocyanineblue dye. In one embodiment, the manufactured inorganic storage phosphorlayer has a coefficient of variation in the linearized pixel value thatis less than or equal to 70% of that of an equivalent solvent coatedstorage phosphor screen. In one embodiment, the manufactured inorganicstorage phosphor layer has a coefficient of variation in the linearizedpixel value that is less than or equal less than or equal to half thatof an equivalent solvent coated storage phosphor screen. In certainexemplary embodiments, the inorganic storage phosphor material has 95%of its particles to be ≤6.8 microns in diameter. In certain exemplaryembodiments, the inorganic storage phosphor material has 95% of itsparticles to be ≤6.8 microns in diameter and 95% of the particles to be≥1.0 microns in diameter. In certain exemplary embodiments, the extrudedor manufactured inorganic storage phosphor layer has 95% of itsinorganic storage phosphor material particles to be ≤6.8 microns indiameter and 95% of its inorganic storage phosphor material particles tobe ≥1.0 microns in diameter.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In this document, the terms “including” and “inwhich” are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, device,article, or process that includes elements in addition to those listedafter such a term in a claim are still deemed to fall within the scopeof that claim.

Certain exemplary method and/or apparatus embodiments according to theapplication can provide virtual definition of the base of a dentalvirtual model. Exemplary embodiments according to the application caninclude various features described herein (individually or incombination).

While the invention has been illustrated with respect to one or moreimplementations, alterations and/or modifications can be made to theillustrated examples without departing from the spirit and scope of theappended claims. In addition, while a particular feature of theinvention can have been disclosed with respect to only one of severalimplementations/embodiments, such feature can be combined with one ormore other features of the other implementations/embodiments as can bedesired and advantageous for any given or particular function. The term“at least one of” is used to mean one or more of the listed items can beselected. The term “about” indicates that the value listed can besomewhat altered, as long as the alteration does not result innonconformance of the process or structure to the illustratedembodiment. Further, “exemplary” indicates the description is used as anexample, rather than implying that it is an ideal. Other embodiments ofthe invention will be apparent to those skilled in the art fromconsideration of the specification and practice of the inventiondisclosed herein. It is intended that the specification and examples beconsidered as exemplary only, with a true scope and spirit of theinvention being indicated by at least the following claims.

The invention claimed is:
 1. A free standing inorganic storage phosphorpanel comprising: an inorganic storage phosphor layer including at leastone polymer, an inorganic storage phosphor material and a copperphthalocyanine blue dye; wherein the inorganic storage phosphor layer isformed by melt compounding the at least one polymer, inorganic storagephosphor material, and copper phthalocyanine blue dye at a level greaterthan or equal to 12 ppm with respect to the phosphor to form a meltcompounded material and by then melt extruding, injection molding, orhot pressing the melt compounded material; and wherein the inorganicstorage phosphor layer has a coefficient of variation in the linearizedpixel value that is less than or equal to 0.7.
 2. The storage phosphorpanel of claim 1, wherein the coefficient of variation in the linearizedpixel value is less than or equal to 0.5.
 3. The storage phosphor panelof claim 1, wherein the coefficient of variation in the linearized pixelvalue is less than or equal to 0.4.
 4. The storage phosphor panel ofclaim 1, wherein the inorganic storage phosphor material comprisesparticles in which 95% of the particles are less than or equal to 6.8microns in diameter and 95% of the particles are greater than or equalto 1.0 microns in diameter.
 5. The storage phosphor panel of claim 1,wherein the inorganic storage phosphor material comprises particles inwhich 95% of the particles are less than or equal to 6.8 microns indiameter.
 6. The storage phosphor panel of claim 1, wherein theinorganic storage phosphor material comprises particles in which 50% ofthe particles are less than or equal to 3.8 microns in diameter.
 7. Thestorage phosphor panel of claim 1, wherein the polymer comprises atleast one thermoplastic polyolefin.
 8. A free standing inorganic storagephosphor panel comprising: an inorganic storage phosphor layer includingat least one thermoplastic polyolefin, an inorganic storage phosphormaterial and a copper phthalocyanine blue dye; wherein the inorganicstorage phosphor material comprises particles in which 95% of theparticles are less than or equal to 6.8 microns in diameter and 95% ofthe particles are greater than or equal to 1.0 microns in diameter;wherein the inorganic storage phosphor layer is formed by meltcompounding the at least one polymer, inorganic storage phosphormaterial, and copper phthalocyanine blue dye to form a melt compoundedmaterial and by then melt extruding, injection molding, or hot pressingthe melt compounded material; and wherein the inorganic storage phosphorlayer has a coefficient of variation in the linearized pixel value thatis less than or equal to 0.4.
 9. A method for manufacturing an inorganicstorage phosphor panel comprising: melt compounding an inorganic storagephosphor layer including at least one thermoplastic polyolefin, aninorganic storage phosphor material and a copper phthalocyanine blue dyeto produce a melt compounded material; melt extruding, injectionmolding, or hot pressing the melt compounded material to form amanufactured inorganic storage phosphor panel; and wherein themanufactured inorganic storage phosphor layer has a coefficient ofvariation in the linearized pixel value that is less than or equal to0.4.
 10. The method of claim 9, wherein the manufactured inorganicstorage phosphor layer comprises particles in which 95% of the particlesare less than or equal to 6.8 microns in diameter and 95% of theparticles are greater than or equal to 1.0 microns in diameter.